1. Field of the Invention
This invention relates to a static mixer for flowing media and, in particular, to a static mixer having a tubular enclosure which encloses guide surfaces.
2. Description of the Prior Art
A static mixer is defined as a mixer without moving parts. The media to be mixed (gases, liquids or pastes of low viscosity) are driven in the same direction, for instance, by means of blowers, pumps or presses through tubular enclosures which contain inserts with guide surfaces for mixing the media. The maintenance of these mixers is essentially confined to the disassembly and reassembly of the mixer components for cleaning, which is easily done. Also, the operating and manufacturing costs are low and the possibilities for installation in plants for chemical processes are many. Static mixers can be used, for instance, for the preparation of suspensions or emulsions, and in the plastics industry, for the admixing of hardeners, pigments and other additives to liquid synthetic resins or for the mixing of polymers and copolymers.
In one known type of static mixer inserts which comprise several guide surfaces are employed. These surfaces divide the flowing media into layers and combine the substreams flowing in the layers to form a new overall stream so that originally adjacent substreams come to lie at a distance from each other. A multiplicity of such inserts is placed in tandem in such a manner that the layer formation caused by the succeeding insert is perpendicular to the layer formation generated at the preceding insert.
In another known type of static mixer, the inserts employed comprise several alternatingly left-handed and right-handed helices, each rotated by 180.degree., which are arranged coaxially with the tubular enclosure and whose intersecting surfaces are perpendicular to each other. The mixing action in this type of mixer is brought about by the division of the flowing media at the one end of each helix into two substreams which are rotated by 180.degree. as they pass through the helix and are brought together again at the other end. At the next helix, the just combined stream is again divided into two substreams perpendicular to the previous intersecting surfaces.
The operation of the previously described known static mixers is, therefore, based on the repeated division at each helix of the flowing media into substreams and the subsequent recombination of these substreams. By lining up many helices, one obtains good mixing, but at the expense of an overall structural length for the mixer which is disadvantageously quite large.
It is therefore an object of the present invention to realize a static mixer having guide surfaces arranged to achieve good mixing action in a length of enclosure which is reasonably short.